Apparatus for cleaning swimming pools in an automatic manner are well known in the art, an excellent example of which is that disclosed in U.S. Pat. No. 3,295,540, Pool Cleaning Apparatus by Robert Ortega. The apparatus of that patent includes wheel-like floats driven by pressurized water jets to move along the pool walls. Several trailing hoses are also connected to the pressurized water. Movement of water out the hose ends produces an undulating movement of the hoses that dislodges dirt, leaves and the like which may be adhering to the wall surfaces. The loosened materials become suspended in the water and are removed by the filter apparatus which is a customary part of the water conditioning apparatus for the pool. In the past, such apparatus has been maintained sufficiently buoyant that it would float on the top of the surface of the water and includes parts of the apparatus extending substantially above the water surface.
It has also been found that it is advisable to provide a cover over the swimming pool when the pool is not in use, both to aid in keeping dirt, dust and other waste materials from being thrown or otherwise deposited in the pool, as well as reducing the amount of heat needed to keep the pool at a given temperature. That is, during extended periods when a pool is not being used, covering the pool will maintain the pool at a higher temperature than would normally occur if it were left exposed to the air, thereby reducing the amount of energy needed to heat the pool. This is due to the fact that the cover prevents cooling air from directly contacting the pool water, and as well to the fact that heat being radiated away from the water will not be able to escape as readily into the surrounding air as would be the case with an uncovered pool.
Even though a pool is covered, it still needs cleaning since dirt and dust which has been deposited in the pool prior to the cover being placed thereover, must be removed in a timely manner to prevent it forming a tightly adherent layer on the pool plaster surface. However, known pool cleaners cannot operate effectively underneath a cover since the buoyant characteristics cause a substantial protrusion above the water level and these parts on contacting the pool cover stop movement and operation of the cleaner.